Various audio and/or video processing systems receive audio data at a particular rate and receive video data having an associated aspect ratio and image resolution. In certain situations, it may be necessary to change the rate of the audio data or change the aspect ratio, image resolution, or other characteristic of the video data. When changing these characteristics, it may be necessary to create new data points by interpolating the new data point from two or more known data elements. This process of creating new data points from existing data is often referred to as “resampling data”.
An example of video resampling reduces (i.e., resamples) an original video image having a 480×720 pixel resolution to a new video image having a smaller size, such as a 280×352 pixel resolution. Alternatively, an original video image can be resampled to a new video image having a larger size. With respect to audio data, an audio data clip having a duration of 2.3 seconds may be resampled to reduce the audio data clip duration to 2.2 seconds. Alternatively, an audio data clip can be resampled to increase the duration of the audio clip.
Resampling is commonly used with video data when encoding video data for display at various spatial resolutions to fit particular displays. Resampling is also used to enable spatial transcoding (the process of converting data from one format to another). A particular type of video signal is referred to as an “interlaced video signal”. Interlaced video signals first generate all odd numbered lines on a video display, then generate all even numbered lines on the display. Resampling can be used to de-interlace these types of video signals (i.e., determining the value of a pixel between two pixels in even numbered lines or in odd numbered lines).
An existing procedure for resampling is a four-step process. First, the received data is pre-filtered. Second, the filtered data is downsampled (e.g., taking every Mth data element). Third, the downsampled data is upsampled (e.g., adding N zeros between data elements). Finally, the upsampled data is post-filtered to complete the resampling process. This four-step process for resampling requires long filters to obtain an acceptable visual quality of the data.
Accordingly, there is a need for a resampling procedure that provides a new technique with improved results while maintaining a high quality resampled video image.